Thin film magnetic head and method of manufacturing the same

ABSTRACT

On a first magnetic layer  27,  is formed a ring-shaped insulating layer  28  whose air bearing surface side edge defines a reference position for a throat height, and after forming a write gap layer  29,  a second magnetic layer  30  is formed such that the second magnetic layer extends over the ring-shaped insulating layer  28.  The write gap layer is selectively removed by performing an etching process using the second magnetic layer as a mask, and then the first magnetic layer is partially removed over a part of its thickness to form a trim structure. After forming a thin film coil  33, 35  within the ring-shaped insulating layer, a third magnetic layer is formed to be brought into contact with a rear portion of the second magnetic layer  31.  The third magnetic layer may be contacted with a surface, a surface and side walls or a surface, side walls and an end surface of rear portion of the second magnetic layer. In the thin film magnetic head, a pole chip defining a track width is narrow, magnetic flux saturation and leakage of magnetic flux can be suppressed in spite of a short throat height, and a high recording efficiency can be attained. The invention provides a method of manufacturing easily the thin film magnetic head having such superior performance with a high yield.

[0001] This is a Continuation of application Ser. No. 09/592,918 filedJun. 13, 2000 which in turn is a Division of application Ser. No.09/099,461 filed Jun. 18, 1998 now U.S. Pat. No. 6,130,805 issued Oct.10, 2000. The entire disclosure of the prior applications is herebyincorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a thin film magnetic head and amethod of manufacturing the same, and more particularly to technique ofimproving a performance of an inductive type thin film writing magnetichead of a composite type thin film magnetic head constructed by stackingthe inductive type thin film writing magnetic head and amagnetoresistive type reading magnetic head one on the other.

[0004] 2. Description of the Related Art

[0005] Recently a surface recording density of a hard disc device hasbeen improved, and it has been required to develop a thin film magnetichead having an improved performance accordingly. In order to improve aperformance of a reading magnetic head, a reproducing head utilizing amagnetoresistive effect has been widely used. As the reproducingmagnetic head utilizing the magnetoresistive effect, an AMR reproducingelement utilizing a conventional anisotropic magnetoresistive (AMR)effect has been widely used. There has been further developed a GMRreproducing element utilizing a giant magnetoresistive (GMR) effecthaving a resistance change ratio higher than the normal anisotropicmagnetoresistive effect by several times. In the present specification,these AMR and GMR reproducing elements are termed as a magnetoresistivereproducing element or MR reproducing element.

[0006] By using the AMR reproducing element, a very high surfacerecording density of several gigabits per a unit square inch has beenrealized, and a surface recording density can be further increased byusing the GMR element. By increasing a surface recording density in thismanner, it is possible to realize a hard disc device which has a verylarge storage capacity of more than 10 gigabytes and is still small insize.

[0007] A height of a magnetoresistive reproducing element is one offactors which determine a performance of a reproducing head including amagnetoresistive reproducing element. This height is generally called MRHeight, here denoted by MRH. The MR height MRH is a distance measuredfrom an air bearing surface on which one edge of the magnetoresistivereproducing element is exposed to the other edge of the element remotefrom the air bearing surface. During a manufacturing process of themagnetic head, a desired MR height MRH can be obtained by controlling anamount of polishing the air bearing surface.

[0008] At the same time, a performance of a recording head has been alsorequired to be improved. In order to increase a surface recordingdensity, it is necessary to make a track density on a magnetic recordmedium as high as possible. For this purpose, a width of a pole portionat the air bearing surface has to be reduced to a value within a rangefrom several micron meters to several sub-micron meters. In order tosatisfy such a requirement, the semiconductor manufacturing process hasbeen adopted for manufacturing the thin film magnetic head. One offactors determining a performance of an inductive type thin film writingmagnetic film is a throat height TH. This throat height TH is a distanceof a pole portion measured from the air bearing surface to an edge of aninsulating layer which serves to separate electrically a thin film coilfrom the air bearing surface. It has been required to shorten thisdistance as small as possible. Also this throat height TH is determinedby an amount of polishing the air bearing surface.

[0009]FIGS. 1a, 1 b-9 a, 9 b are cross sectional views showingsuccessive steps of a known method of manufacturing a conventionaltypical thin film magnetic head, said cross sectional views being cutalong a plane perpendicular to the air bearing surface and cut along aplane parallel with the air bearing surface. FIGS. 10-12 are a crosssectional view illustrating a completed thin film magnetic head cutalong a plane perpendicular to the air bearing surface, a crosssectional view of the pole portion cut along a plane parallel with theair bearing surface, and a plan view depicting the pole portion. Thismagnetic head belongs to a composite type thin film magnetic head whichis constructed by stacking an inductive type thin film writing magnetichead and a magnetoresistive type thin film reading magnetic head one onthe other.

[0010] At first, as illustrated in FIGS. 1a and 1 b, on a substrate 1made of a hard non-magnetic material such as aluminum-titan-carbon(AlTiC), is deposited an insulating layer 2 made of alumina (Al₂O₃) andhaving a thickness of about 5-10 μm. Then, as depicted in FIGS. 2a and 2b, a bottom shield layer 3 constituting a magnetic shield for the MRreproducing magnetic head is formed to have a thickness of about 3 μm onthe insulating layer.

[0011] Then, after depositing by sputtering a shield gap layer 4 made ofan alumina with a thickness of 100-150 nm as shown in FIGS. 3a and 3 b,a magnetoresistive layer 5 having a thickness of several tens nanometers and being made of a material having the magnetoresistive effect,and the magnetoresistive layer is shaped into a desired pattern by ahighly precise mask alignment.

[0012] Next, as represented in FIGS. 4a and 4 b, a shield gap layer 6 isformed such that the electromagnetic layer 5 is embedded within theshield gap layers 4, 6.

[0013] Then a magnetic layer 7 made of a permalloy and having athickness of 3 μm is formed as shown in FIGS. 5a and 5 b. This magneticlayer 7 serves not only as an upper shield layer for magneticallyshielding the MR reproducing element together with the above mentionedbottom shield layer 3, but also as a bottom magnetic layer of theinductive type writing thin film magnetic head to be manufactured later.Here, for the sake of explanation, the magnetic layer 7 is called afirst magnetic layer, because this magnetic layer constitutes one ofmagnetic layers forming the thin film writing magnetic head.

[0014] Next, after forming, on the first magnetic layer 7, a write gaplayer 8 made of a nonmagnetic material such as alumina to have athickness of about 200 nm, a second magnetic layer 8 made of a magneticmaterial having a high saturated magnetic flux density such as apermalloy (Ni: 50 wt %, Fe: 50 wt %) and iron nitride (FeN) and thesecond magnetic layer is shaped into a desired pattern by means of aprecise mask alignment.

[0015] This second magnetic layer 24 having a desired pattern is calleda pole chip and a track width is determined by a width of the pole chip.

[0016] During this process, a dummy pattern 9′ for connecting the bottompole (first magnetic layer) to an upper pole (third magnetic layer) tobe formed later is formed. Then a through hole can be easily formedafter mechanical polishing or chemical-mechanical polishing (CMP).

[0017] In order to prevent an increase of an effective track width, thatis, in order to prevent a spread of a magnetic flux at the lower poleduring a writing operation, the gap layer 8 and bottom pole (firstmagnetic layer) near the pole chip 9 are removed by an ion beam etchingsuch as an ion milling. This condition is illustrated in FIG. 5, andthis structure is called a trim structure. It should be noted that thisportion constitutes the pole portion of the first magnetic layer.

[0018] Next, as illustrated in FIGS. 6a and 6 b, an insulating layer 10such as an alumina layer is formed to have a thickness of about 3 μm,and then an assembly is flattened by, for instance CMP.

[0019] After that, an electrically insulating photo-resist layer 11 isformed in accordance with a given pattern by a highly precise maskalignment, and then a first layer of a thin film coil 12 made of, forinstance copper is formed on the photo-resist layer 11.

[0020] Next, as depicted in FIGS. 7a and 7 b, an insulating photo-resistlayer 13 is formed on the thin film coil 12 by a highly precise maskalignment, a surface is flattened by baking at a temperature of, forinstance 250-300° C.

[0021] Furthermore, as shown in FIGS. 8a and 8 b, on the thus flattenedsurface of the photo-resist layer 13, a second layer thin film coil 14is formed. Then, a photo-resist layer 15 is formed on the second layerthin film coil 14 by a highly precise mask alignment, and a bakingprocess is carried again at a temperature of, for instance 250° C.

[0022] A reason for forming the photo-resist layers 11, 13 and 15 by ahighly precise mask alignment is that the throat height TH and MR heightare determined with respect to edges of these photo-resist layers on aside of the pole portion.

[0023] Next, as shown in FIGS. 9a and 9 b, a third magnetic layer 16made of, for instance a permalloy is formed on the second magnetic layer(pole chip) 9 and photo-resist layers 11, 13 and 15 such that the thirdmagnetic layer has a thickness of 3 μm and is shaped into a desiredpattern.

[0024] The third magnetic layer 16 is brought into contact with thefirst magnetic layer 7 at a position remote from the pole portion bymeans of the dummy pattern 9′, and therefore the thin film coil 12, 14pass through a closed magnetic yoke structure constituted by the first,second and third magnetic layers.

[0025] Furthermore, an overcoat layer 25 made of an alumina is depositedon an exposed surface of the third magnetic layer 16.

[0026] Finally, a side wall at which the magnetoresistive layer 5 andgap layer 8 are formed is polished to form an air bearing surface (ABS)18. During the formation of the air bearing surface 18, themagnetoresistive layer 5 is also polished to obtain an MR reproducingelement 19. In this manner, the above mentioned throat height TH and MRheight MRH are determined by the polishing. This condition is shown inFIG. 10. In an actual manufacturing process, contact pads forestablishing electrical connections to the thin film coils 12, 14 and MRreproducing element 19 are formed, but these contact pads are not shownin the drawings.

[0027] As shown in FIG. 10, an angle θ between a straight line Sconnecting side edges of the photo-resist layers 11, 13 and 15 isolatingthe thin film coils 12, 14 and an upper surface of the third magneticlayer 16 is called an apex angle. This apex angle is one of importantfactors for determining a property of the thin film magnetic headtogether with the throat height TH and MR height MRH.

[0028] Furthermore, as shown in the plan view of FIG. 12, a width W ofthe pole portion 20 of the second magnetic layer 9 and third magneticlayer 16 is small. A width of tracks recorded on a record medium isdetermined by said width W, and therefore it is necessary to make thiswidth W as small as possible in order to realize a high surfacerecording density. It should be noted that in the drawing, the thin filmcoils 12, 14 are denoted to be concentric for the sake of simplicity.

[0029] In the known method of manufacturing the thin film magnetic head,there is a special problem in the formation of the upper pole (yokepole) after the formation of the thin film coil in a precise manneralong the outwardly protruded coil portion, particularly along aninclined portion (apex) thereof, said coil portion being covered withthe photo-resist insulating layers. That is to say, in the known method,upon forming the upper pole, after an upper pole material such aspermalloy is deposited by plating on the outwardly protruded coilportion having a height of about 7-10 μm, a photo-resist is applied tohave a thickness of 3-4 μm, and then the layer is shaped into a givenpattern by utilizing the photolithography. Since a thickness of thephoto-resist layer provided on the upper portion of the coil portionshould be at least 3 μm, the photo-resist layer has to be applied suchthat a portion of the photo-resist at a bottom of the outwardlyprotruded coil portion would have a thickness of 8-10 μm.

[0030] On the other hand, in order to form a narrow track of therecording head near the edges of the photo-resist insulating layers (forinstance, layers 11 and 13 in FIG. 7), the upper pole formed on thewrite gap layer provided on the surface of the outwardly protruded coilportion as well as on the flat surface should be patterned to have awidth of about 1 μm, said coil portion and flat portion having a leveldifference of about 10 μm. Therefore, it is necessary to form thephoto-resist layer having a thickness of 8-10 μm and a pattern having awidth of 1 μm.

[0031] However, when a narrow pattern having a width of 1 μm is to beformed with the thick photo-resist layer having a thickness of 8-10 μm,a top pole which can realize a narrow track could hardly be manufacturedaccurately due to a deformation of a pattern by light reflection duringa light exposure in a photolithography and an inevitable decrease in aresolution caused by a large thickness of the photo-resist layer.

[0032] Under the above circumstances, as shown in the above explainedknown method, the above problem has been solved by writing data with theaid of the pole chip which can realize a narrow track width and afterforming the pole chip, the upper pole is connected to the pole chip.That is to say, the division structure is adopted, in which the upperyoke is divided into the pole chip defining the track width and theupper pole for introducing a magnetic flux into the pole chip.

[0033] However, the thin film magnetic head, particularly the recordingmagnetic head formed in the above mentioned manner still has thefollowing problems.

[0034] (1) The throat height TH and MR height MRH are determined, whilethe edge of the insulating layer isolating the thin film coil on a sideof the pole portion is used as a positional reference, and theinsulating layer is generally made of an organic insulating photo-resistlayer and thus is liable to be affected by heat. Therefore, theinsulating film is liable to be melt or softened by the heatingtreatment at about 250° C. during the formation of the thin film coil,and a pattern of the insulating layer might be deformed. Moreover, areference position of zero throat height is determined by an end of thepole chip 9 opposite to the air bearing surface 18, and the edge of thepole chip pattern is rounded off due to a fact that the pole chip has anarrow width W, and therefore a position of the end of the pole chipmight be shifted. In this manner, in the composite type thin filmmagnetic head, it is difficult to determine the reference position ofthroat height zero accurately, and thus the thin film magnetic headhaving desired throat height TH and MR height MRH according to thedesired design values could not be manufacture with a high yield.

[0035] (2) The surface of the pole chip 9 is coupled with the surface ofthe third magnetic layer 16. In order to make the width W of the polechip narrow as explained above and in order to attain a good magneticproperty, a length of the pole chip has to be short such as about 1 μm.Therefore, a contact area of the pole chip and third magnetic layer issmall. Moreover, the third magnetic layer is brought into contact withthe pole chip perpendicularly, and thus a magnetic flux is liable to besaturated at this portion, a writing property, particularly a magneticflux rise time is degraded.

[0036] (3) If there is an alignment error in the photolithography forforming the third magnetic layer 16 on the pole chip 9 having the narrowwidth W, a center of the pole chip 9 and a center of the pole portion 20of the third magnetic layer 16 viewed from the air bearing surface mightbe shifted relative to each other. If the center of the pole chip 9 isdeviated from the center of the pole portion 20 of the third magneticlayer 16, there might be produced a large leakage of the magnetic fluxfrom the pole portion of the third magnetic layer and data might bewritten by this leaked magnetic flux. Therefore, an effective trackwidth is increased and data might be recorded in a region other than adesired region into which the data has to be recorded.

SUMMARY OF THE INVENTION

[0037] The present invention has for its object to provide a thin filmmagnetic head, in which the above mentioned problems can be solved andthe insulating layer constituting a positional reference for the airbearing surface is not melt or softened by a heating treatment forforming the thin film coil at a temperature of about 250° C., and thusthe throat height TH and MR height MRH accurately corresponding todesired design values can be obtained stably.

[0038] It is another object of the invention to provide a thin filmmagnetic head, in which a surface area at a contact with the pole chipand the upper pole can be effectively increased, and therefore undesiredsaturation of the magnetic flux at the pole portion can be prevented.

[0039] It is another object of the invention to provide a thin filmmagnetic head, in which undesired increases in an effective track widthand in a manufacturing yield can be mitigated.

[0040] It is another object of the invention to provide a thin filmmagnetic head, in which a track width can be reduced by decreasing aheight of the thin film coil, and the number of coil windings can beeffectively increased.

[0041] It is another object of the invention to provide a method ofmanufacturing the thin film magnetic head having the above mentionedsuperior characteristics in an accurate manner with a high yield.

[0042] According to the invention, a thin film magnetic head comprises:

[0043] a first magnetic layer having a pole portion;

[0044] a second magnetic layer having a pole portion whose end surfaceconstitutes an air bearing surface together with said pole portion ofthe first magnetic layer, said pole portion of the second magnetic layerhaving a width defining a width of a record track on a magnetic recordmedium to be opposed to the air bearing surface;

[0045] a third magnetic layer which is brought into contact with saidsecond magnetic layer on a side opposite to said first magnetic layerand is magnetically coupled with said first magnetic layer at a rearposition remote from the air bearing surface;

[0046] a gap layer made of a non-magnetic material and being interposedat least between said pole portion of the first magnetic layer and saidpole portion of the second magnetic layer;

[0047] a thin film coil having a portion which is supported by aninsulating material in an electrically isolated manner between saidfirst magnetic layer and said second and third magnetic layers; and

[0048] a substrate supporting said first, second and third magneticlayers, gap layer and thin film coil;

[0049] wherein a band-shaped or strip-shaped insulating layer having atleast a portion whose edge on a side of the pole portion defines areference position for the air bearing surface is provided on said firstmagnetic layer, at least a surface of said insulating layer opposing tosaid first magnetic layer is covered with the non-magnetic materialconstituting said gap layer, and said thin film coil is provided in arear region with respect to said insulating layer.

[0050] In the thin film magnetic head according to the invention, thethird magnetic layer may be coupled with said second magnetic layer onlyat the surface of the second magnetic layer or at the surface and sidewalls of the second magnetic layer or at the surface, side walls and endsurface of the second magnetic layer.

[0051] According to the invention, said insulating layer may havevarious plan configuration, but it is most preferable to form thering-shaped insulating layer and the thin film coil is arranged in aninner area of the ring. Furthermore, the band-shaped insulating layermay be preferably made of an inorganic insulating material such asalumina, silicon oxide and silicon nitride.

[0052] In a preferable embodiment of the thin film magnetic headaccording to the invention, said second magnetic layer is formed suchthat it extends not only over the pole portion of the first magneticlayer, but also over the band-shaped insulating layer situating behindthe pole portion. In this case, it is preferable to gradually increase awidth of the second magnetic layer on the band-shaped insulating layer.A widening angle of the rear portion of the second magnetic layer ispreferably made identical with that of the third magnetic layer, saidangle being 30-180°.

[0053] In the thin film magnetic head according to the invention, it ispreferable to make said second magnetic layer of a magnetic materialhaving a high saturation flux density such as permalloy (Ni: 50 Wt %, Fe50 Wt %), iron nitride (FeN), Fe—Cr—Zr based amorphous alloy and Fe—Cbased amorphous alloy.

[0054] In a preferable embodiment of the thin film magnetic headaccording to the invention, a front end of said third magnetic layer isretarded from the air bearing surface such that a contact portionbetween the second magnetic layer and the third magnetic layer is notexposed on the air bearing surface. In this case, it is preferable tomake a retarding distance of the front end of the third magnetic layersubstantially equal to the throat height TH.

[0055] Furthermore, in another preferable embodiment of the thin filmmagnetic head according to the invention, the thin film magnetic head isconstructed as a composite type thin film magnetic head by providing areading magnetoresistive element in an electrically insulated andmagnetically shielded manner such that an edge of the magnetoresistiveelement is exposed on said air bearing surface.

[0056] According to the invention, a method of manufacturing a thin filmmagnetic head comprises the steps of:

[0057] forming a first magnetic layer having a pole portion such thatthe first magnetic layer is supported by a substrate;

[0058] forming a band-shaped insulating layer on said first magneticlayer, said insulating layer having at least a portion whose edgedefines a reference position for an air bearing surface;

[0059] forming a gap layer made of a non-magnetic material on at leastsaid pole portion of the first magnetic layer and on said insulatinglayer;

[0060] forming a second magnetic layer on said gap layer at least at aportion which situates on said first magnetic layer;

[0061] forming a thin film coil in a rear region on a side of theband-shaped insulating layer opposite to said air bearing surface suchthat the thin film coil is supported by an insulating material in anelectrically isolated manner;

[0062] forming a third magnetic layer such that the third magnetic layeris coupled with said second magnetic layer as well as with said firstmagnetic layer at a rear portion opposite to said air bearing surface;and

[0063] polishing the substrate, pole portions of the first and secondmagnetic layers and gap layer sandwiched by these magnetic layers toform the air bearing surface which is to be opposed to a magnetic recordmedium.

[0064] In the method of manufacturing the thin film magnetic headaccording to the invention, the third magnetic layer may be coupled withthe surface of the second magnetic layer or with the surface and sidewalls of the second magnetic layer or with the surface, side walls andend surface of the second magnetic layer.

[0065] In the method of manufacturing the thin film magnetic headaccording to the invention, it is preferable to form said secondmagnetic layer such that not only the pole portion of the first magneticlayer, but also the insulating layer behind the pole portion are coveredwith the second magnetic layer. In this case, it is preferable toincrease gradually a width of the rear portion of the second magneticlayer.

[0066] In a preferable embodiment of the method of manufacturing thethin film magnetic head according to the invention, said band-shapedinsulating layer is formed as a ring-shape, and prior to the formationof the thin film coil, a surface of the second magnetic layer, a surfaceof the ring-shaped insulating layer and an inner area surrounded by thering-shaped insulating layer are covered with a non-magnetic andnon-conductive film. In this case, it is particularly preferable topolish the surface of the rear portion of the second magnetic layer anda surface of the non-magnetic and non-conductive film such that thesesurfaces become co-planer. By proving such a flat surface, the thin filmcoil can be formed much more accurately.

[0067] In the method of manufacturing the thin film magnetic headaccording to the invention, it is preferable to form said third magneticlayer such that a front end of the third magnetic layer is retarded fromthe air bearing surface and a contact portion of the second and thirdmagnetic layers is not exposed on the air bearing surface.

[0068] Moreover, in the method of manufacturing the thin film magnetichead according to the invention, it is also possible to constitute acomposite type thin film magnetic head by forming a magnetoresistivereproducing element between said substrate and said first magnetic layersuch that the element is magnetically shielded and electricallyisolated. In this case, a first shield layer is formed on the substrate,the magnetoresistive material layer embedded within a shield gap layeris formed on the first shield layer, and said first magnetic layer alsoserving as a second shield layer is formed. During a polishing step forforming the air bearing surface, said magnetoresistive material layer aswell as the first shield layer and shield gap layer are polished to formthe magnetoresistive reproducing element having an edge exposed on theair bearing surface.

BRIEF DESCRIPTION OF THE DRAWINGS

[0069]FIGS. 1a, 1 b-9 a, 9 b are cross sectional views cut along a planeperpendicular to the air bearing surface as well as a plane parallelwith the air bearing surface and showing successive steps ofmanufacturing a known composite type thin film magnetic head;

[0070]FIG. 10 is a cross sectional view of the completed known thin filmmagnetic head cut along a plane perpendicular to the air bearingsurface;

[0071]FIG. 11 a cross sectional view showing the pole portion of thecompleted known thin film magnetic head cut along a plane perpendicularto the air bearing surface;

[0072]FIG. 12 is a plan view illustrating the completed known thin filmmagnetic head;

[0073]FIGS. 13a, 13 b-18 a, 18 b are cross sectional views cut along aplane perpendicular to the air bearing surface as well as along a planeparallel with the air bearing surface showing successive steps of anembodiment of the thin film magnetic head manufacturing method accordingto the invention;

[0074]FIG. 19 is a plan view illustrating a second magnetic layer shownin FIG. 18;

[0075]FIG. 20 is a plan view depicting another embodiments of the secondmagnetic layer;

[0076]FIGS. 21a, 21 b-25 a, 25 b are cross sectional views cut along aplane perpendicular to the air bearing surface as well as along a planeparallel with the air bearing surface showing succeeding steps;

[0077]FIG. 26 is a plan view illustrating a shape of the third magneticlayer suitable for the second magnetic layer;

[0078]FIGS. 27a and 27 b are cross sectional views cut along a planeperpendicular to the air bearing surface as well as a plane parallelwith the air bearing surface showing a completed thin film magnetic headaccording to the invention;

[0079]FIG. 28 is a plan view illustrating the completed thin filmmagnetic head according to the invention;

[0080]FIGS. 29a and 29 b are cross sectional views cut along a planeperpendicular to the air bearing surface as well as along a planeparallel with the air bearing surface showing another embodiment of thethin film magnetic head according to the invention;

[0081]FIGS. 30a-30 i are plan views showing several embodiments of theband-shaped insulating layer provided in the thin film magnetic headaccording to the invention;

[0082]FIGS. 31a, 31 b-34 a, 34 b are cross sectional views cut along aplane perpendicular to the air bearing surface as well as along a planeparallel with the air bearing surface illustrating successive steps of asecond embodiment of the method of manufacturing the composite type thinfilm magnetic head according to the invention;

[0083]FIG. 35 is a plan view depicting a condition shown in FIG. 34;

[0084]FIGS. 36a, 36 b and 37 a, 37 b are cross sectional views cut alongplanes perpendicular to and parallel with the air bearing surfaceshowing succeeding steps;

[0085]FIG. 38 is a perspective view illustrating a condition shown inFIG. 37;

[0086]FIGS. 39a, 39 b and 40 a, 40 b are cross sectional views cut alongplanes perpendicular to and parallel with the air bearing surfaceshowing succeeding steps;

[0087]FIG. 41 is a perspective view illustrating a condition shown inFIG. 40;

[0088]FIGS. 42a and 42 b are cross sectional views cut along planesperpendicular to and parallel with the air bearing surface showing acompleted thin film magnetic head;

[0089]FIG. 43 is a plan view depicting a shape of the band-shapedinsulating layer in another embodiment of the thin film magnetic headaccording to the invention;

[0090]FIG. 44 is a plan view showing the band-shaped insulating layer inanother embodiment of the thin film magnetic head according to theinvention; and

[0091]FIG. 45 is a diagrammatic plan view illustrating a configurationof a coupled portion of the second magnetic layer in another embodimentof the thin film magnetic head according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0092] FIGS. 13-26 show successive steps of an embodiment of the methodof manufacturing the thin film magnetic head according to the invention,and FIGS. 27 and 28 are longitudinal cross sectional view and plan view,respectively showing a completed thin film magnetic head according tothe invention. In the drawings showing the steps, (a) represents a crosssectional view cut along a plane perpendicular to an air bearing surfaceand (b) illustrates a cross sectional view cut along a plane parallelwith the air bearing surface. The thin film magnetic head of the presentembodiment is constructed as a composite type thin film magnetic headhaving an inductive type writing magnetic head and a MR reproducingelement stacked one on the other.

[0093] At first, as shown in FIGS. 13a and 13 b, on a substrate 21 madeof an AlTiC, is deposited an insulating layer 42 made of an aluminahaving a thickness of about 3-5 μm.

[0094] Next, as shown in FIGS. 14a and 14 b, on the alumina insulatinglayer 22, a permalloy layer constituting a lower magnetic shield layer23 is deposited to have a thickness of about 3 μm by using aphoto-resist film as a mask by means of sputtering.

[0095] Next, an insulating layer 24′ made of an alumina is formed tohave a thickness of about 4-6 μm as illustrated in FIGS. 15a and 15 band a surface of this insulating layer is flattened by, for instanceCMP. Then, a shield gap layer 24 made of an alumina is deposited bysputtering to have a thickness of 100-200 nm as illustrated in FIGS. 16aand 16 b, and then a magnetoresistive layer 25 forming the MRreproducing element is formed to have a thickness of several tens nanometers and the magnetoresistive layer is patterned into a desired shapeby means of a highly precise mask alignment. After that a shield gapfilm 26 is formed such that the magnetoresistive layer 25 is embeddedwithin the shield gap layers 24, 26. Then, a first magnetic layer 27having a thickness of about 3-4 μm is selectively formed.

[0096] After that, in order to remove any step, an alumina layer havinga thickness of 5-6 μm is formed on a whole surface, and then thisalumina layer is processed by CMP to expose the surface of the firstmagnetic layer 27.

[0097] Next, a band-shaped insulating layer 28 is formed by means of aphoto-resist to have a thickness of 2-5 μm and a width of 3-7 μm, saidinsulating layer including at least a portion whose edge opposing to thepole portion defines a reference position with respect to the throatheight TH and apex angle. In the present embodiment, said band-shapedinsulating layer is formed as a ring-shaped insulating layer, butaccording to the invention, it is always necessary to form thering-shaped insulating layer. That is to say, it is sufficient for theband-shaped insulating layer 28 to have the portion which defines thereference position with respect to the throat height TH, and thus aninner portion of the ring-shaped insulating layer is not necessary.However, when the ring-shaped insulating layer 28 having the innerportion is formed, the thin film coil can be manufactured accurately ina later step.

[0098] Next, as shown in FIGS. 18a and 18 b, a write gap layer 29 madeof an alumina and having a thickness of 100-300 nm is formed at least onthe pole portion of the first magnetic layer 36 and ring-shapedinsulating layer 28. In this case, it is preferable to cover an innerarea of the band-shaped insulating layer 28 with a non-magnetic layerconstituting the write gap layer 29, because an insulation from thefirst magnetic layer can be maintained. When the surface of theband-shaped insulating layer 28 is covered with the alumina insulatinglayer 29, the following merit can be obtained.

[0099] The throat height TH is defined as a distance between the airbearing surface and the edge of the ring-shaped insulating layer 28 on aside of the pole portion, but in actual manufacturing, since the edge ofthe insulating layer could not been seen, it is assumed that said edgeis formed at a desired position and the air bearing surface is polishedsuch that a desired throat height TH can be obtained by using this edgeposition as the reference position.

[0100] On the other hand, during a later step of forming the thin filmcoil, a heating treatment is carried out at about 250° C., and duringthis heating treatment, the photo-resist layer constitutingthe-ring-shaped insulating layer 28 is melt and a pattern size of theinsulating layer is shifted. Therefore, a position of the abovementioned edge of the photo-resist insulating layer 28 is also shifted,and thus a size of the throat height TH formed by taking the edgeposition as the reference position might be deviated from a desireddesign value.

[0101] The MR height MRH which is defined as a height of themagnetoresistive reproducing element measured from the air bearingsurface is also determined by an amount of polishing the air bearingsurface like as the throat height TH. This polishing is performed whilethe edge of the ring-shaped insulating layer 28 opposing to the poleportion is utilized as the reference position, and thus if a position ofthis edge of the insulating layer is shifted during the heatingtreatment, the MR height is also deviated from the desired design value.

[0102] Moreover, if the photo-resist layers 33, 36 constituting thering-shaped insulating layer 28 and the insulating layer which isolatesthe thin film coil to be explained later are melt, the apex angle θdefined by an inclination angle of the side surface of these insulatinglayers might be also deviated. The performance of the thin film magnetichead also depends on this apex angle θ, and might be sometimes affectedby the deviation of the apex angle.

[0103] Therefore, it is important that a position of the edge ofphoto-resist layer forming the ring-shaped insulating layer is notvaried even under the heating treatment of about 250° C. carried out theformation of the thin film coil. In the present embodiment, afterforming the ring-shaped photo-resist insulating layer 28, the aluminainsulating layer 29 constituting the write gap is formed such that thephoto-resist insulating layer is covered with the alumina insulatinglayer as shown in FIGS. 17a and 17 b, and therefore the edge of thephoto-resist insulating layer 28 is no more shifted by the heatingtreatment and undesired deviations of the throat height TH as well asthe MR height MRH and apex angle θ from the desired design values can beeffectively suppressed.

[0104] Next, as illustrated in FIGS. 18a and 18 b, a second magneticlayer 30 (pole chip) defining the track width W is selectively formed tohave a thickness of about 1-4 μm. Then, the write gap in the vicinity ofthe pole chip is selectively removed an opening, and the first magneticlayer 27 exposed in the opening is etched by, for instance an ion beammilling, to form the pole portion.

[0105] It should be noted that in the present invention, as shown by Hin FIG. 18a, the pole portion means a portion of a region extending fromthe outer edge of the ring-shaped insulating layer 28 to an end surfaceof the stacked body, along said portion the first magnetic layer 27,write gap layer 29 and second magnetic layer 30 being adjoined with thewidth W (see FIG. 18b). Therefore, in a final product, after polishingthe end surface to form the air bearing surface, the pole portionbecomes a region extending from the outer edge of the ring-shapedinsulating layer 28 to the air bearing surface and is identical with thethroat height TH.

[0106] According to the invention, upon forming the pole chip, it isimportant that the second magnetic layer 30 is extended not only overthe pole portion but also over the surface of the ring-shaped insulatinglayer 28 which is positioned behind the pole portion as depicted in FIG.19. In the known thin film magnetic head in which the top pole isdeposited on the pole chip, a contact area between the pole chip and thetop pole is small and an end surface of the top pole is perpendicular tothe surface of the pole chip. Therefore, a magnetic flux is liable to besaturated at this portion and a sufficiently satisfactory writingproperty could not be obtained. According to the present invention, acontact area between the pole chip and the top pole is not limited tothe pole portion, but is extended up to a rear portion such that theabove mentioned saturation of magnetic flux can be effectively removedand a sufficiently satisfactory writing property can be attained. Inthis case, if a sufficiently large contact area can be obtained, thecontact region between the pole chip and the top pole may be restrictedto a rear region with respect to the pole portion. In thisspecification, the term “rear” means a direction remote from the airbearing surface.

[0107] According to the invention, a shape of the rear portion of thepole chip behind the pole portion may be modified in various ways. Forinstance, the rear portion of the pole chip may be extended in astraight forward manner as shown in FIG. 19, or may be gradually widenedas depicted in FIG. 20. At any rate, according to the invention, it issufficient that the pole chip and top pole are contacted with each otherin the rear region behind the pole portion.

[0108] It should be noted that a length h of the backwardly extendedportion of pole chip behind the pole portion may be preferably set toabout 2-5 μm which does not exceed a thickness of the ring-shapedinsulating layer 28, and more particularly to a value substantiallyequal to a thickness of the top pole.

[0109] Furthermore, in the embodiment shown in FIG. 20, the rear portionof the pole chip behind the pole portion is widened at an angle of about90°, but according to the invention, this widening angle is not limitedonly to such an angle, but may be set to an angle not larger than 180°,and a more preferably widening angle range is 45-180°.

[0110] In this manner, when the rear portion of the pole chip is widenedlike a fan as shown in FIG. 20, not only the above mentioned saturationof magnetic flux does not occur, but also a more accurate patterncontrol in the photolithography can be performed and the throat heightTH can be much more accurately controlled.

[0111] After forming the second magnetic layer 30 as explained above, afirst layer thin film coil is to be formed in a region surrounded by thering-shaped insulating layer 28. Prior to the formation of the thin filmcoil, a non-magnetic and non-conductive layer such as an alumina layerhaving a thickness of about 0.5-1.5 μm is deposited as illustrated inFIGS. 21a and 21 b. By covering at least the area on which the thin filmcoil is to be formed with the non-magnetic and non-conductive layer 31,an isolation between the first magnetic layer 27 and the thin film coilcan be improved and a leakage of magnetic field can be effectivelyavoided. Moreover, it is preferable to cover not only the inside of thering-shaped insulating layer 28, but also the whole surfaces of thering-shaped insulating layer and second magnetic layer (pole chip) 30.

[0112] Next, as shown in FIGS. 22a and 22 b, after forming a first layerthin film coil 32 made of a copper on the region surrounded by thering-shaped insulating layer 28, an insulating photo-resist layer 33 isformed with a highly precise mask alignment, and then a heatingtreatment is conducted at a temperature of, for instance 250° C. inorder to obtain a flat surface. In this manner, according to theinvention, the first layer thin film coil 32 is formed on the regionsurrounded by the ring-shaped insulating layer 28, and therefore a wholeheight of the thin film coil can be decreased. That is to say, in theknown thin film magnetic head, since the thin film is formed on theinsulating layer, when two or three layer thin film coil is formed inorder to improve a performance of the writing magnetic head, a height ofthe coil portion is increased. Then, it is difficult to reduce a trackwidth. According to the invention, at least the first layer thin filmcoil is formed within the ring-shaped insulating layer 28, an apexheight can be deceased accordingly. On the other hand, if the apexheight is made substantially identical with that of the known magnetichead, the number of coil turns may be increased accordingly and asuperior performance may be attained.

[0113] Next, as shown in FIGS. 23a and 23 b, on a whole surface isformed an alumina insulating layer 34 having a thickness of 4-5 μm, andthen the surface is flattened by, for instance CMP such that the firstlayer thin film coil 32 is covered with the insulating layer 34, but thepole chip (second magnetic layer), contact portions of the first layerthin film coil and a through hole (not shown) for connecting the bottompole and top pole (third magnetic layer) are exposed.

[0114] After that, as illustrated in FIGS. 24a and 24 b, after forming asecond layer thin film coil 35, a photo-resist layer 36 is formed on thesecond layer thin film coil. Then, in order to flatten the surface, aheating treatment is conducted at a temperature of, for instance 250° C.

[0115] Next, a third magnetic layer (top pole) 37 made of, for instancepermalloy and having a thickness of 3 μm is selectively formed on thesecond magnetic layer (pole chi) 30 and photo-resist layer 36 inaccordance with a given pattern as shown in FIGS. 25a and 25 b.

[0116] Upon forming the third magnetic layer 37, it is preferable that afront end of the third magnetic layer is retarded from the air bearingsurface by a distance equal to the throat height TH as shown in FIG. 25a(in the drawing, shown by L). This is due to a fact that when the frontend of the third magnetic layer extends up to the air bearing surface,if a positional relationship between the pole chip and the tope pole isshifted largely on one side, a data writing might be carried out alsothrough the front end of the top pole and an effective track width mightbe widened, but when the front end of the third magnetic layer isretarded from the air bearing surface, such a demerit can be avoided.

[0117] It should be noted that if the front end of the top pole isretarded from the air bearing surface in the known thin film magnetichead, a contact area between the pole chip and the top pole is decreasedaccordingly and a leakage of magnetic flux could not be avoided.According to the present invention, since this contact area can besufficiently large by providing the rear portion behind the poleportion, even if the front end of the top pole is retarded from the airbearing surface, undesired leakage of magnetic flux does not occur.

[0118] Upon forming the third magnetic layer 37, it is desired that thethird magnetic layer follows a configuration of the second magneticlayer 30 as shown in FIG. 20. Moreover, when the widening angle of thesecond magnetic layer 30 is small such as 30-60° as illustrated in FIG.26, a front end portion of the third magnetic layer 37 may be formed tofollow the shape of the second magnetic layer such that the thirdmagnetic layer is also gradually widened at the widening angle of30-60°, and a rear portion of the third magnetic layer may be furtherwidened at a desired widening angle.

[0119] In this manner, by forming the third magnetic layer such that itis gradually widened to cover the second magnetic layer 30, even if anerror occurs in an alignment between the pole chip 30 and the top pole37, a variation in a contact area therebetween is remained small and aleakage of magnetic flux can be avoided.

[0120] It should be noted that the third magnetic layer 37 is broughtinto contact with the first magnetic layer 27 by means of the throughhole provided at a position remote from the pole portion, and the thinfilm coil 32, 35 passes through a closed magnetic path constituted bythe first, second and third magnetic layers.

[0121] Next, as depicted in FIGS. 27a and 27 b, an overcoat layer 38made an alumina and the like is deposited on an exposed surface of thethird magnetic layer 37.

[0122] Finally, as illustrated in FIGS. 27 and 28, a side wall on whichthe magnetoresistive layer 25 and gap layer 29 is polished to form anair bearing surface 39, which is to be opposed to a magnetic recordmedium.

[0123] During the polishing, the edge of ring-shaped insulating layer 28on a side of the pole portion is utilized as the reference position forthe air bearing surface 39, and therefore the throat height TH, MRheight MRH and apex angle θ can be accurately determined in accordancewith desired design values.

[0124]FIGS. 29a and 29 b are cross sectional views showing anotherembodiment of the thin film magnetic head according to the invention, inwhich the pole chip 30 is formed to have a large thickness. Byincreasing a thickness of the pole chip 30, a distance over which thefront end of the top pole 37 is retarded from the air bearing surface 39can be increased. As a result of this, even if the front end of the toppole 37 is closer to the air bearing surface due to a variation inprocess for the air bearing surface, a writing operation to anothertrack can be prevented and thus an undesired increase in an effectivetrack width can be much more effectively prevented.

[0125] In the embodiments so far explained, the band-shaped insulatinglayer 28 having at least the portion whose edge on a side of the poleportion serves as the reference position for the air bearing surface isformed as the elliptical ring-shape as shown in FIG. 30a. According tothe invention, the band-shaped insulating layer is not limited to such aring-shaped one, but may be formed in various shapes. For instance,substantially ring-shapes shown in FIGS. 30b and 30 c, or parts ofelliptical, octagonal and rectangular ring-shapes as illustrated inFIGS. 30d, 30 e and 30 f, respectively, or rectilinear shapes asdepicted in FIGS. 30g, 30 h and 30 i.

[0126] Now a second embodiment of the method of manufacturing the thinfilm magnetic head according to the invention will be explained withreference to FIGS. 31-42. In these drawings, a represents a crosssectional view cut along a plane perpendicular to the air bearingsurface and b shows a cross sectional view of the pole portion cut alonga plane parallel with the air bearing surface. Also in this embodiment,a composite type thin film magnetic head is manufactured by forming amagnetoresistive type reading thin film magnetic head on a substrate andthen forming an inductive type thin film magnetic head on themagnetoresistive type thin film magnetic head.

[0127] As shown in FIGS. 31a and 31 b, on a main substrate 21 made of anAlTiC, is deposited an insulating layer 72 made of an alumina having athickness of about 3-5 μm. In the present specification, an assembly ofthese main substrate 71 and insulating layer 72 is called substrate orwafer 73. Moreover, in the specification, the insulating layer means afilm having at least an electrically insulating property, and may or maynot have a non-magnetic property. Generally used material such asalumina has both the electrically insulating and non-magneticproperties, an insulating layer sometimes means a non-magnetic layer.

[0128] Furthermore, in a practical manufacturing, after forming a numberof thin film magnetic heads on a wafer in a matrix form, the wafer isdivided into a plurality of bars, a end surface of a bar is polished toform air bearing surfaces, and finally the bar is divided intorespective thin film magnetic heads. Therefore, during the formation onthe wafer, the end surface of the thin film magnetic head does notappear, but for the sake of explanation, this end surface is shown.

[0129] Next, on the insulating layer 72 of the substrate 73, a permalloylayer constituting a bottom shield layer 74 for the magnetoresistivetype thin film magnetic head is formed to have a thickness of about 3μm. The bottom shield layer 74 is formed in accordance with a givenpattern by a plating method using a photo-resist mask.

[0130] Next, a GMR layer 76 is formed on the bottom shield layer 74 suchthat the GMR layer is embedded in a shield gap layer 75 made of aluminaas illustrated in FIGS. 32a and 32 b. A thickness of this shield gaplayer 75 may be 0.2 μm. On the shield gap layer 75 in which the GMRlayer 76 is embedded, is formed a first magnetic layer 77 made of apermalloy and having a thickness of 3-4 μm, said first magnetic layerconstituting the top shield for the GMR layer as well as the bottom poleof the inductive thin film magnetic head.

[0131] Next, in order to isolate the first magnetic layer 77 from a thinfilm coil to be formed later as well as to prevent a leakage of magneticflux, an alumina insulating layer 78 having a thickness of 0.3-0.7 μm isformed on the first magnetic layer 77, and then on the aluminainsulating layer, is formed an insulating layer 79 made of silicon oxideto have a thickness of 0.5-2.0 μm as shown in FIGS. 33a and 33 b. In thepresent embodiment, this insulating layer made of silicon oxide isformed by the plasma CVD while the substrate is heat at temperature of150° C., but it may be formed by a sputtering at a room temperature.Furthermore, the insulating layer may be made of other inorganicmaterials such as alumina and silicon nitride instead of silicon oxide.

[0132] Next, the insulating layer made of silicon oxide is selectivelyetched to form a band-shaped insulating layer 79, and then the aluminainsulating layer 78 is selectively etched by a reactive ion etching asshown in FIGS. 34a and 34 b, said reactive ion etching being performedby using a freon based gas such as CF₄ and SF₆ or a chlorine based gassuch as Cl₂ and BCl₂. FIG. 35 is a plan view showing the thus formedring-shaped insulating layer 79. About a center of the ring-shapedinsulating layer 79, there is formed an opening 78 a in the insulatinglayer 78, and the first magnetic layer 77 is exposed in this opening. InFIG. 35, for the sake of clarity, a third magnetic layer constitutingthe pole chip and a thin film coil to be formed later are shown byimaginary lines.

[0133] Next, as shown in FIGS. 36a and 36 b, a write gap layer 80 madeof an alumina and having a thickness of 0.1-0.3 μm is formed inaccordance with a given pattern on the exposed surface of the firstmagnetic layer 77 and surfaces of the insulating layers 78 and 79.According to the invention, a thickness of said ring-shaped insulatinglayer 79 is substantially larger than that of the write gap layer 80.Then, a second magnetic layer 81 constituting the pole chip defining thetrack width and made of a magnetic material having a high saturationmagnetic flux density is formed to have a thickness of 3-4 μm. Themagnetic material having a high saturation magnetic flux density may beNiFe (50%, 50%) or FeN. The second magnetic layer 81 constituting thepole chip may be formed in accordance with a given pattern by a platingmethod or by a dry-etching after sputtering.

[0134] According to the present invention, as shown in a plan view ofFIG. 35, the second magnetic layer 81 may preferably include a poleportion 81 a and a connecting portion 81 b which extends over thering-shaped insulating layer 79, a width of said connecting portionbeing gradually increased. This connecting portion may be formed into atriangular shape or pentagonal shape as illustrated in FIG. 35. Sincethe record track width is determined by a width W of the pole portion 81a of the second magnetic layer 81, it is preferable to form said widthnarrow such as 0.5-1.2 μm.

[0135] Next, as shown in FIGS. 37a and 37 b, a part of the gap layer 80adjacent to the pole portion 81 a is selectively removed by a reactiveion etching process using a freon based gas such as CF₄ and SF₆ or achlorine based gas such as Cl₂ and BCl₂ to exposed the underlying firstmagnetic layer 77. Then, an ion beam etching process using an argon gasis conducted, while the pole portion 81 a of the second magnetic layer81 and ring-shaped insulating layer 79 as a mask such that the exposedsurface of the first magnetic layer 77 is dug down over a depth of about0.5 μm to form the trim structure. The construction of the pole portionat this processing stage is also shown in a perspective view of FIG. 38.

[0136] In the present embodiment, since the ring-shaped insulating layer79 is made of an inorganic insulating material, a position of the edgeof the insulating is not deviated and the insulating layer is notpeeled-off during the reactive ion etching and ion beam etching forobtaining the trim structure. Therefore, a manufacturing yield can beimproved and a durability of the magnetic head can be increased.

[0137] Next, as illustrated in FIGS. 39a and 39 b, a first layer thinfilm coil 83 is formed within an area surrounded by the ring-shapedinsulating layer 79 such that the thin film coil is supported by aphoto-resist layer 82 in an electrically isolated manner, and then asecond layer thin film coil 85 is formed such that the tin film coil issupported by a photo-resist layer 84 in an electrically isolated manner.In the present embodiment, an air space of 2-3 μm is formed between thephoto-resist layers 82, 84 and the second magnetic layer 81.

[0138] Then, as shown in FIGS. 40a and 40 b, a third magnetic layer 86having a thickness of 3-4 μm is formed in accordance with a givenpattern such that a front end of the third magnetic layer on a side ofthe air bearing surface is brought into contact with the connectingportion 81 b of the second magnetic layer 81 and a rear end of the thirdmagnetic layer remote from the air bearing surface is connected to thefirst magnetic layer 77 via the opening 78 a formed in the insulatinglayer 78 as depicted in FIG. 41. In this manner, a contact area betweenthe second and third magnetic layers 81 and 86 can be increased, andthus a leakage of magnetic flux at the pole portion can be furthereffectively suppressed. Such an advantage is particularly important whena width of the first layer 81 constituting the pole chip is not largerthan 100 μm.

[0139] Furthermore, as illustrated in FIGS. 42a and 42 b, an overcoatlayer 87 made of an alumina and having a thickness of 20-30 μm is formedon a whole surface. As stated above, in the practical manufacturingprocess, the wafer is cut into bars and a side face of a bar is polishedto form the air bearing surface. In the present embodiment, a positionof the edge of the ring-shaped insulating layer 79 on a side of the airbearing surface is used as the reference position and this position isnot shifted during the manufacturing, and therefore it is possible toobtain easily the throat height TH having a desired design value.

[0140] In the present embodiment, the band-shaped insulating layer 79having a large thickness is formed in a ring-shape and the thin filmcoil 83, 85 is arranged within the ring. According to the invention, theband-shaped insulating layer is not always necessary to be formed into aring-shape, but may be formed in any other shape. For instance, theinsulating layer may be formed as a frame shape as shown in FIG. 43 ormay be formed rectilinearly as illustrated in FIG. 44. According to theinvention, as long as the band-shaped insulating layer 79 has an airbearing surface side edge which can define the throat height zeroposition and has a thickness larger than that of the write gap layer, itmay be formed into any shape as shown in FIGS. 30a-30 i.

[0141] Moreover, in the present embodiment, the connecting portion 81 bof the second magnetic layer 81 and the third magnetic layers 86 arejoined to each other at the surface, side walls and end surface of theconnecting portion. However, according to the invention, the thirdmagnetic layer 86 may be brought into contact with the surface and sidewalls of the connecting portion 81 b of the second magnetic layer 81 asillustrated in FIG. 44.

[0142] The present invention is not limited to the embodiments explainedabove, but many alternations and modifications may be conceived by thoseskilled in the art. For instance, in the above mentioned embodiments,the connecting portion of the second magnetic layer and the frontportion of the third magnetic layer lying over the connecting portionare formed to be gradually widened. The second magnetic layer 91 may beformed such that a pole portion 91 a is connected to a connectingportion 91 b at right angles as shown in FIG. 45. In this case, awidening angle of the connecting portion 91 a of the second magneticlayer 91 may be considered to be 180°. Also in this case, the front endportion of the third magnetic layer 96 extending over the connectingportion 91 b of the second magnetic layer 91 may be formed to have aconstant width in accordance with a shape of the underlying connectingportion. Even if the widening angle is set to 180°, it has beenexperimentally confirmed that the improved over write property can beobtained and an increase in the effective track width can be suppressed.

[0143] Further, in the above embodiments, the reading magnetoresistivetype thin film magnetic head is provided on the substrate and thewriting inductive type thin film magnetic head is stacked on the readingmagnetic head, but according to the invention this stacking order may bereversed. In the above embodiments, the magnetoresistive element isformed by a GMR element, but it may be formed by an AMR element.Moreover, according to the invention, the reading thin film magnetichead is not limited to the magnetoresistive element, but may be formedby any other thin film magnetic head. It should be further noted thatthe reading thin film magnetic head is not always necessary, but onlythe inductive type thin film magnetic head may be provided.

[0144] According to the invention, the second magnetic layerconstituting the pole chip may be advantageously made of any kind of amagnetic material having a high saturation magnetic flux density such asa Fe—Cr—Zr based amorphous alloy and a Fe—C based amorphous alloy inaddition to the above mentioned permalloy (Ni: 50%, Fe: 50%) and ironnitride (FeN). It should be noted that plural layers of two or more thantwo kinds of these materials may be stacked.

[0145] The first and third magnetic layers may be advantageously made ofknown magnetic materials having a high saturation magnetic flux densityin addition to the above mentioned permalloy (Ni: 80%, Fe: 20%).

[0146] The write gap layer may be made of an oxide such as Al₂O₃ andSiO₂, or a nitride such as AlN, BN and SiN, or an electricallyconductive but magnetically non-conductive material such as Au, Cu andNiP.

[0147] In the embodiments shown in the drawings, the insulating layerhaving the edge on a side of the air bearing surface side gives thereference position for the air bearing surface is made of aphoto-resist, but according to the invention, this insulating layer maybe made of alumina, silicon or silicon nitride.

[0148] In the first embodiment, the insulating layer 28 is made of aphoto-resist and in the second embodiment, the insulating layer 78 ismade of a silicon oxide, but they may be made of other inorganicinsulating material. However, these insulating layers are preferablymade of an inorganic insulating material from a view point that theselayers serve as a mask in the etching process for forming the trimstructure.

[0149] According to the present invention, the band-shaped insulatinglayer is provided on the first magnetic layer such that the edge of theinsulating layer on a side of the air bearing surface defines thereference position for the air bearing surface, and this insulatinglayer is covered with the write gap layer made of alumina. Therefore,the insulating layer is not melt by the heating treatment during theformation of the thin film coil and a position of the edge is notshifted, and thus the throat height TH, MR height MRH and apex angle θcan be formed accurately in accordance with desired design values.

[0150] Therefore, according to the invention, there is always existent adesired relationship between the throat height TH and the MR height MRH,and thus the writing head and reading head can be remained always in anoptimum condition. As the result of this, it is possible to provide acomposite type thin film magnetic head having a superior performance.

[0151] Moreover, according to the invention, the second magnetic layer(pole chip) and the third magnetic layer top pole) are joined to eachother not only at the pole portion, but also at the rear portion havinga larger surface area, and the magnetic flux generated by the coil isnot saturated and a leakage of the magnetic flux at the connectingportion can be suppressed, and thus data can be recorded efficiently ona very narrow track. In this manner, it is possible to obtain asatisfactory writing performance. That is to say, the third magneticlayer may be brought into contact with the surface, or the surface andside walls, or the surface, side walls and end surface of the connectingportion of the second magnetic layer, and a very large contact area canbe obtained.

[0152] Moreover, by widening the rear portion of the second magneticlayer, a contact area between the top pole and the pole chip can beincreased, and thus a leakage of the magnetic flux at this portion canbe effectively prevented.

[0153] By widening the third magnetic layer covering the second magneticlayer, even if an error is introduced in an alignment of these layers, acontact area is not changed and a leakage of magnetic flux can be stillavoided.

[0154] Furthermore, according to the invention, the front end of thethird magnetic layer is retarded from the air bearing surface and acontact portion between the second and third magnetic layers is notexposed on the air bearing surface, and therefore even if a relativeposition of the top pole with respect to the pole chip deviates viewedfrom the air bearing surface, the writing operation through the top polecan be avoided and an increase in the effective track width can beprevented.

[0155] Moreover, according to the invention, since the apex height canbe reduced as compared with the known thin film magnetic head, a trackwidth of the recording head can be effectively reduced, or if the apexangle is set to be substantially equal to that of the known head, thenumber of coil windings can be increased accordingly and the recordingperformance can be improved.

[0156] In the embodiment of the thin film magnetic head according to theinvention, in which the band-shaped insulating layer is formed into aring-shape and the thin film coil is formed within the ring, a height ofthe thin film coil consisting of two or three layers can be reduced by adistance substantially equal to a thickness of the insulating layer, andthus the apex angle can be decreased and the number of coil windings canbe increased. In this manner, an efficiency of the thin film coil can beimproved.

[0157] Further, as shown in the second embodiment, when the band-shapedinsulating layer having a large thickness is made of an inorganicmaterial, the edge of the inorganic insulating layer is hardly shiftedduring the etching process for forming the trim structure, and thus aportion of the insulating layer situating under the second magneticlayer constituting the pole chip is neither damaged nor peeled-off and aposition of the insulating layer is not shifted. Therefore, adegradation of the performance of the thin film magnetic head can besuppressed. Further, since the insulating layer is not peeled-off, nooil and polishing liquid could not be retained between the insulatinglayer and the first magnetic layer, a manufacturing yield can beincreased and a durability of the thin film magnetic head can beprolonged.

What is claimed is:
 1. A thin film magnetic head comprising: a substratehaving a major surface; a first magnetic layer formed on or above themajor surface of the substrate and having a pole portion; a secondmagnetic layer having a pole portion which is opposed to said poleportion of the first magnetic layer via a write gap layer andconstitutes an air bearing surface together with said pole portion ofthe first magnetic layer; a third magnetic layer having one endconnected to said second magnetic layer and the other end remote fromthe air bearing surface magnetically coupled with the first magneticlayer; and at least one layer of thin film coil having a portion formedbetween said first and second magnetic layers; wherein said at least onelayer of thin film coil is embedded within an organic insulating layer;and an inorganic insulating layer is provided on the organic insulatinglayer such that a surface of the inorganic insulating layer opposite tothe organic insulating layer is coplanar with a surface of the secondmagnetic layer opposite to the write gap layer.
 2. The thin filmmagnetic head according to claim 1, wherein said organic insulating filmis made of photo-resist and said inorganic insulating layer is made ofalumina.
 3. The thin film magnetic head according to claim 1, furthercomprising a second layer of thin film coil formed on said coplanarsurface of the inorganic insulating layer.